-
Belle Collaboration,
V. Bhardwaj,
K. Miyabayashi,
I. Adachi,
H. Aihara,
D. M. Asner,
V. Aulchenko,
T. Aushev,
T. Aziz,
A. M. Bakich, [......],
J. Yamaoka,
Y. Yamashita,
S. Yashchenko,
Y. Yook,
C. Z. Yuan,
C. C. Zhang,
Z. P. Zhang,
V. Zhilich,
V. Zhulanov,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: We report measurements of $B \to \chi_{c1} \gamma K$ and $\chi_{c2} \gamma K$
decays using $772 \times 10^{6}$ $B\bar{B}$ events collected at the
$\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy
$e^+e^-$ collider. Evidence of a new resonance in the $\chi_{c1} \gamma$ final
state is found with a statistical significance of $3.8 \sigma$. This state has
a mass of $3823.1 \pm 1.8 {(stat)} \pm 0.7 {(syst)}$ MeV/$c^2$, a value that is
consistent with theoretical expectations for the previously unseen $1^3 D_2$
$c\bar{c}$ meson. We find no other narrow resonance and set upper limits on the
branching fractions of the $X(3872) \to \chi_{c1} \gamma$ and $\chi_{c2}
\gamma$ decays.
04/2013;
-
Belle Collaboration,
Z. Q. Liu,
C. P. Shen,
C. Z. Yuan,
I. Adachi,
H. Aihara,
D. M. Asner,
V. Aulchenko,
T. Aushev,
T. Aziz, [......],
B. D. Yabsley,
J. Yamaoka,
Y. Yamashita,
S. Yashchenko,
Y. Yook,
Y. Yusa,
C. C. Zhang,
Z. P. Zhang,
V. Zhilich,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: The cross section for $e^+ e^- \to \pi^+ \pi^- J/\psi$ between 3.8 GeV and
5.5 GeV is measured with a 967 fb$^{-1}$ data sample collected by the Belle
detector at or near the $\Upsilon(nS)$ ($n = 1,\ 2,\ ...,\ 5$) resonances. The
Y(4260) state is observed, and its resonance parameters are determined. In
addition, an excess of $\pi^+ \pi^- J/\psi$ production around 4 GeV is
observed. This feature can be described by a Breit-Wigner parameterization with
properties that are consistent with the Y(4008) state that was previously
reported by Belle. In a study of $Y(4260) \to \pi^+ \pi^- J/\psi$ decays, a
structure is observed in the $M(\pi^\pm\jpsi)$ mass spectrum with $5.2\sigma$
significance, with mass $M=(3894.5\pm 6.6\pm 4.5) {\rm MeV}/c^2$ and width
$\Gamma=(63\pm 24\pm 26)$ MeV/$c^{2}$, where the errors are statistical and
systematic, respectively. This structure can be interpreted as a new charged
charmonium-like state.
03/2013;
-
R. Barate,
D. Buskulic,
D. Decamp,
P. Ghez,
C. Goy,
J.-P. Lees,
A. Lucotte,
E. Merle,
M.-N. Minard,
J.-Y. Nief, [......],
J.M. Nachtman,
J. Nielsen,
W. Orejudos,
Y.B. Pan,
Y. Saadi,
I.J. Scott,
J. Walsh,
Sau Lan Wu,
X. Wu,
G. Zobernig
[show abstract]
[hide abstract]
ABSTRACT: An improved measurement of the forward-backward asymmetry in decays is presented, based on a sample of 4.1 million hadronic Z decays collected by ALEPH between 1991 and 1995. Data are analysed as a function of polar angle of the event axis and b purity. The event tagging efficiency and mean b-jet hemisphere charge are measured directly from data. From the measured forward-backward jet charge asymmetry, the b quark asymmetry at is determined to be: AbFB=0.1017±0.0038(stat.)±0.0032(syst.). In the context of the Standard Model this corresponds to a value of the effective weak mixing angle of sin2θWeff=0.23109±0.00096.
Physics Letters B 03/2013; · 3.95 Impact Factor
-
R. Barate,
D. Buskulic,
D. Decamp,
P. Ghez,
C. Goy,
J.-P. Lees,
A. Lucotte,
E. Merle,
M.-N. Minard,
J.-Y. Nief, [......],
J.M. Nachtman,
J. Nielsen,
W. Orejudos,
Y.B. Pan,
Y. Saadi,
I.J. Scott,
J. Walsh,
Sau Lan Wu,
X. Wu,
G. Zobernig
[show abstract]
[hide abstract]
ABSTRACT: The flavour changing neutral current decay b→sγ has been detected in hadronic Z decays collected by ALEPH at LEP. The signal is isolated in lifetime-tagged events by the presence of a hard photon associated with a system of high momentum and high rapidity hadrons. The background processes are normalised from the data themselves. The inclusive branching ratio is measured to beconsistent with the Standard Model expectation via penguin processes.
Physics Letters B 03/2013; · 3.95 Impact Factor
-
R. Barate,
D. Buskulic,
D. Decamp,
P. Ghez,
C. Goy,
J.-P. Lees,
A. Lucotte,
E. Merle,
M.-N. Minard,
J.-Y. Nief, [......],
J.M. Nachtman,
J. Nielsen,
W. Orejudos,
Y.B. Pan,
Y. Saadi,
I.J. Scott,
J. Walsh,
Sau Lan Wu,
X. Wu,
G. Zobernig
[show abstract]
[hide abstract]
ABSTRACT: Starting from a sample of four million hadronic Z decays collected with the ALEPH detector at LEP, 404 charged and neutral B mesons are fully reconstructed and used to look for resonant structure in the Bπ system. An excess of events is observed above the expected background in the Bπ mass spectrum at a mass ≈5.7 GeV/c2, consistent with the production and decay to B(∗)π of the B∗∗ states predicted by Heavy Quark Symmetry (HQS). In the framework of HQS, it is found that the mass of the state is MeV/c2 and the relative production rate of the B∗∗ system is . In the same sample of B mesons, significant Bπ± charge-flavour correlations are observed, which may prove important for tagging the initial B state in future CP violation studies.
Physics Letters B 03/2013; · 3.95 Impact Factor
-
R. Barate,
D. Buskulic,
D. Decamp,
P. Ghez,
C. Goy,
S. Jezequel,
J.-P. Lees,
A. Lucotte,
M.-N. Minard,
J.-Y. Nief, [......],
J. Nielsen,
W. Orejudos,
Y.B. Pan,
Y. Saadi,
I.J. Scott,
J. Walsh,
Sau Lan Wu,
X. Wu,
J.M. Yamartino,
G. Zobernig
[show abstract]
[hide abstract]
ABSTRACT: The mass of the W boson is obtained from reconstructed invariant mass distributions in W-pair events. The sample of W pairs is selected from 10.65 pb−1 collected with the ALEPH detector at a mean centre-of-mass energy of 172.09 GeV. The invariant mass distribution of simulated events are fitted to the experimental distributions and the following W masses are obtained:The statistical errors are the expected errors for Monte Carlo samples of the same integrated luminosity as the data. The combination of these three measurements gives:
Physics Letters B 03/2013; · 3.95 Impact Factor
-
D. Buskulic,
I. De Bonis,
D. Decamp,
P. Ghez,
C. Goy,
J.-P. Lees,
A. Lucotte,
M.-N. Minard,
P. Odier,
B. Pietrzyk, [......],
M. Schmitt,
I.J. Scott,
V. Sharma,
J.D. Turk,
A.M. Walsh,
Sau Lan Wu,
X. Wu,
J.M. Yamartino,
M. Zheng,
G. Zobernig
[show abstract]
[hide abstract]
ABSTRACT: Searches for supersymmetric particles produced in e+e− collisions at centre-of-mass energies of 130 and 136 GeV have been performed in a data sample of 5.7 pb−1 collected in the autumn of 1995 by the ALEPH detector at LEP. No candidate events were found, allowing limits to be set on the masses and production cross-sections of scalar leptons, scalar tops, charginos and neutralinos. The domains previously excluded at LEP1 are substantially extended. For instance, masses of gaugino-like charginos smaller than 67.8 GeV/c2 are excluded at the 95% C.L. for scalar neutrino masses larger than 200 GeV/c2.
Physics Letters B 03/2013; · 3.95 Impact Factor
-
D. Buskulic,
I. De Bonis,
D. Decamp,
P. Ghez,
C. Goy,
J.-P. Lees,
A. Lucotte,
M.-N. Minard,
J.-Y. Nief,
P. Odier, [......],
W. Orejudos,
Y.B. Pan,
Y. Saadi,
I.J. Scott,
A.M. Walsh,
Sau Lan Wu,
X. Wu,
J.M. Yamartino,
M. Zheng,
G. Zobernig
[show abstract]
[hide abstract]
ABSTRACT: A search for pair production of new heavy leptons has been performed assuming different scenarios for the mixing of the new particles with Standard Model leptons. No candidate events were found in a data sample corresponding to an integrated luminosity of 5.6 pb−1 collected by the ALEPH detector at centre-of-mass energies of 130 and 136 GeV. New limits on production cross-sections and on masses of sequential leptons were obtained which significantly extend the mass regions excluded at LEP1. For instance, charged heavy leptons with masses below 63.5 GeV/c2 are excluded at 95% C.L. for mass differences to the associated neutral lepton of more than 7 GeV/c2.
Physics Letters B 03/2013; · 3.95 Impact Factor
-
D. Buskulic,
I. De Bonis,
D. Decamp,
P. Ghez,
C. Goy,
J.-P. Lees,
A. Lucotte,
M.-N. Minard,
P. Odier,
B. Pietrzyk, [......],
Y. Saadi,
M. Schmitt,
I.J. Scott,
V. Sharma,
A.M. Walsh,
Sau Lan Wu,
X. Wu,
J.M. Yamartino,
M. Zheng,
G. Zobernig
[show abstract]
[hide abstract]
ABSTRACT: Searches for charginos and neutralinos produced in e+e− collisions at centre-of-mass energies of 130 and 136 GeV have been performed under the assumptions that R-parity is not conserved, that the dominant R-parity violating coupling involves only leptonic fields, and that the lifetime of the lightest supersymmetric particle can be neglected. In the 5.7 pb−1 data sample collected by ALEPH, no candidate events were found. As a result, chargino and neutralino masses and couplings are constrained and the domains previously excluded at LEP1 are extended.
Physics Letters B 03/2013; · 3.95 Impact Factor
-
R Barate,
D Buskulic,
D Decamp,
P Ghez,
C Goy,
J.-P Lees,
A Lucotte,
M.-N Minard,
J.-Y Nief,
B Pietrzyk, [......],
J Nielsen,
W Orejudos,
Y.B Pan,
Y Saadi,
I.J Scott,
J Walsh,
Sau Lan Wu,
X Wu,
J.M Yamartino,
G Zobernig
[show abstract]
[hide abstract]
ABSTRACT: The data collected at centre-of-mass energies ranging from 130 to 172 GeV by ALEPH at LEP, corresponding to an integrated luminosity of 27.5 pb−1, are analysed in a search for pair-produced charged Higgs bosons H±. Three analyses are employed to select the , and final states. No evidence for a signal is found. Mass limits are set as a function of the branching fraction for H±→τν. Charged Higgs bosons with masses below 52 GeV/c2 are excluded at 95% C.L. independently of , thus significantly improving on existing limits.
Physics Letters B 03/2013; · 3.95 Impact Factor
-
R Barate,
D Buskulic,
D Decamp,
P Ghez,
C Goy,
J.-P Lees,
A Lucotte,
M.-N Minard,
J.-Y Nief,
B Pietrzyk, [......],
J Nielsen,
W Orejudos,
Y.B Pan,
Y Saadi,
I.J Scott,
J Walsh,
Sau Lan Wu,
X Wu,
J.M Yamartino,
G Zobernig
[show abstract]
[hide abstract]
ABSTRACT: The e+e−→W+W− cross section is measured in a data sample collected by ALEPH at a mean centre-of-mass energy of 172.09 GeV, corresponding to an integrated luminosity of 10.65 pb−1. Cross sections are given for the three topologies, fully leptonic, semi-leptonic and hadronic of a W-pair decay. Under the assumption that no other decay modes are present, the W-pair cross section is measured to be The existence of the triple gauge boson vertex of the Standard Model is clearly preferred by the data. The decay branching ratio of the W boson into hadrons is measured to be , allowing a determination of the CKM matrix element |Vcs|=0.98±0.14(stat.)±0.03(syst.).
Physics Letters B. 03/2013;
-
R. Barate,
D. Buskulic,
D. Decamp,
P. Ghez,
C. Goy,
S. Jezequel,
J.-P. Lees,
A. Lucotte,
M.-N. Minard,
J.-Y. Nief, [......],
J. Nielsen,
W. Orejudos,
Y.B. Pan,
Y. Saadi,
I.J. Scott,
J. Walsh,
Sau Lan Wu,
X. Wu,
J.M. Yamartino,
G. Zobernig
[show abstract]
[hide abstract]
ABSTRACT: The triple gauge-boson couplings, αWΦ, αW and αBΦ, have been measured using 34 semileptonically and 54 hadronically decaying W+W− candidate events. The events were selected in the data recorded during 1996 with the ALEPH detector at 172 GeV, corresponding to an integrated luminosity of 10.65 pb−1. The triple gauge-boson couplings have been measured using optimal observables constructed from kinematic information of W+W− events. The results are in agreement with the Standard Model expectation.
Physics Letters B 03/2013; · 3.95 Impact Factor
-
O. Lutz,
S. Neubauer,
M. Heck,
T. Kuhr,
A. Zupanc,
I. Adachi,
H. Aihara,
D. M. Asner,
T. Aushev,
T. Aziz, [......],
P. Wang,
M. Watanabe,
Y. Watanabe,
K. M. Williams,
E. Won,
H. Yamamoto,
Y. Yamashita,
Z. P. Zhang,
V. Zhilich,
V. Zhulanov
[show abstract]
[hide abstract]
ABSTRACT: We report a search for the rare decays B -> h(*) nu nubar, where h(*) stands
for K+, Ks0, K*+, K*0, pi+, pi0, rho+, rho0 and phi. The results are obtained
from a 711 fb-1 data sample that contains 772 million BB pairs collected at the
Y(4S) resonance with the Belle detector at the KEKB e+e- collider. We search
for signal candidates by fully reconstructing a hadronic decay of the
accompanying B meson and requiring a single h(*) meson left on the signal side.
No significant signal is observed and we set upper limits on the branching
fractions at 90% confidence level. The measurements of B+ -> K*+ nu nubar, B+
-> pi+ nu nubar, B0 -> pi0 nu nubar and B0 -> rho^0 nu nubar provide the
world's currently most restrictive limits.
03/2013;
-
Belle Collaboration,
I. Adachi,
K. Adamczyk,
H. Aihara,
K. Arinstein,
Y. Arita,
D. M. Asner,
T. Aso,
V. Aulchenko,
T. Aushev, [......],
L. M. Zhang,
Z. P. Zhang,
L. Zhao,
V. Zhilich,
P. Zhou,
V. Zhulanov,
T. Zivko,
A. Zupanc,
N. Zwahlen,
O. Zyukova
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of the time-dependent CP violation parameters in B0
-> pi+ pi- decays. The results are obtained from the final data sample
containing 772 million BBbar pairs collected at the Upsilon(4S) resonance with
the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain the
CP violation parameters Acp = +0.33 +/- 0.06 (stat) +/- 0.03 (syst) and Scp =
-0.64 +/- 0.08 (stat) +/- 0.03 (syst), where Acp and Scp represent direct and
mixing-induced CP violation, respectively. From an isospin analysis including
results from other Belle measurements, we rule out 23.8 < phi2 < 66.8 degrees
at the 1 sigma level.
02/2013;
-
Belle Collaboration,
C. Oswald,
P. Urquijo,
J. Dingfelder,
I. Adachi,
H. Aihara,
K. Arinstein,
D. M. Asner,
T. Aushev,
A. M. Bakich, [......],
M. Watanabe,
Y. Watanabe,
K. M. Williams,
E. Won,
H. Yamamoto,
Y. Yamashita,
C. C. Zhang,
Z. P. Zhang,
V. Zhilich,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: We report a measurement of the inclusive semileptonic B_s^0 branching
fraction in a 121 fb^{-1} data sample collected near the Upsilon(5S) resonance
with the Belle detector at the KEKB asymmetric energy e^+ e^- collider. Events
containing B_s^0 pairs are selected by reconstructing a tag side D_s^+ and
identifying a signal side lepton l^+ (l = e, mu) that is required to have the
same-sign charge to ensure that both originate from different B_s^0 mesons. The
B_s^0 -> X^- l^+ nu branching fraction is extracted from the ratio of the
measured yields of D_s^+ mesons and D_s^+ l^+ pairs and the known production
and branching fractions. The inclusive semileptonic branching fraction is
measured to be [10.6 +/- 0.5(stat) +/- 0.7(syst)] %.
12/2012;
-
B. R. Ko,
E. Won,
I. Adachi,
H. Aihara,
K. Arinstein,
D. M. Asner,
T. Aushev,
A. M. Bakich,
K. Belous,
V. Bhardwaj, [......],
G. Varner,
C. H. Wang,
M. -Z. Wang,
P. Wang,
Y. Watanabe,
K. M. Williams,
Y. Yamashita,
C. C. Zhang,
V. Zhilich,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: We search for CP violation in the decay $D^+\rightarrow K^0_S K^+$ using a
data sample with an integrated luminosity of 977 fb$^{-1}$ collected with the
Belle detector at the KEKB $e^+e^-$ asymmetric-energy collider. No CP violation
has been observed and the CP asymmetry in $D^+\rightarrow K^0_S K^+$ decay is
measured to be $(-0.25\pm0.28\pm0.14)%$, which is the most sensitive
measurement to date. After subtracting CP violation due to $K^0-\bar{K}^0$
mixing, the CP asymmetry in $D^+\rightarrow\bar{K}^0 K^+$ decay is found to be
$(+0.08\pm0.28\pm0.14)%$.
12/2012;
-
D. Buskulic,
I. De Bonis,
D. Decamp,
P. Ghez,
C. Goy,
J.-P. Lees,
A. Lucotte,
M.-N. Minard,
P. Odier,
B. Pietrzyk, [......],
Y. Saadi,
M. Schmitt,
I.J. Scott,
V. Sharma,
A.M. Walsh,
Sau Lan Wu,
X. Wu,
J.M. Yamartino,
M. Zheng,
G. Zobernig
[show abstract]
[hide abstract]
ABSTRACT: The B0 - B̄0 average mixing parameter and b forward-backward asymmetry AFB0(b) are measured from a sample of about 4 200 000 Z → qq̄ events recorded with the ALEPH detector at LEP in the years 1990–1995. High transverse momentum electrons and muons produced in b semileptonic decays provide the tag of the quark flavour and of its charge.The average mixing parameter and the pole b asymmetry are measured to be = 0.1246 ± 0.0051stat ± 0.0052syst, AFB0(b) = 0.1008 ± 0.0043stat ± 0.0028syst. The value of sin2θweff = 0.23198 ± 0.00092 is extracted from the asymmetry measurement.
Physics Letters B 12/2012; · 3.95 Impact Factor
-
Damir Buskulic,
I De Bonis,
D Décamp,
P Ghez,
C Goy,
J P Lees,
A Lucotte,
M N Minard,
J Y Nief,
P Odier, [......],
W Orejudos,
Y B Pan,
Y Saadi,
I J Scott,
A M Walsh,
Wu Sau Lan,
X Wu,
J M Yamartino,
M Zheng,
G Zobernig
[show abstract]
[hide abstract]
ABSTRACT: Using data obtained with the ALEPH detector at the Z resonance, a measure based on transverse momentum is shown to exhibit a correlation between the two halves of a hadronic event which cannot be explained by energy-momentum conservation, flavour conservation, the imposition of an event axis or imperfect event reconstruction. Two possible explanations based on Monte Carlo models are examined: a) ARIADNE, with the correlation forming early in the parton shower and with the transition from partons to hadrons playing only a minor part; b) JETSET, with the correlation forming at the fragmentation stage. A correlation technique based on a jet cluster analysis is used to make a comparison of the models with the data. It is concluded that both non-perturbative and perturbative effects make important contributions to the observed correlation.
Zeitschrift für Physik C 12/2012; 73(3):421.
-
I. Adachi,
K. Adamczyk,
H. Aihara,
K. Arinstein,
Y. Arita,
D. M. Asner,
T. Aso,
V. Aulchenko,
T. Aushev,
T. Aziz, [......],
L. M. Zhang,
Z. P. Zhang,
L. Zhao,
V. Zhilich,
P. Zhou,
V. Zhulanov,
T. Zivko,
A. Zupanc,
N. Zwahlen,
O. Zyukova
[show abstract]
[hide abstract]
ABSTRACT: We present a study of the branching fraction of the decay B^0 -> rho^0 rho^0
and the fraction of longitudinally polarized \rho^0 mesons in this decay. The
results are obtained from the final data sample containing $772 \times 10^{6}$
$B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle
detector at the KEKB asymmetric-energy e^+e^- collider. We find $166 \pm 59$
B^0 -> rho^0 rho^0 events, corresponding to a branching fraction of ${\cal
B}(B^0 -> rho^0 rho^0) = (1.02\pm 0.30 (\rm stat) \pm 0.22 (\rm syst))\times
10^{-6} $ with a longitudinally polarization fraction $f_L =
0.21^{+0.18}_{-0.22} (\rm stat) \pm 0.11 (\rm syst)$. The branching fraction's
upper limit is ${\cal B}(B^0 -> rho^0 rho^0) < 1.5 \times 10^{-6}$ at 90%
confidence level. We use the longitudinal polarization fraction to determine
the Cabibbo-Kobayashi-Maskawa matrix angle $\phi_2 = (91.0 \pm 7.2)^{\circ}$
through an isospin analysis in the $B\to\rho\rho$ system. We furthermore obtain
${\cal B}(B^0 -> rho^0 f_0) \times {\cal B}(f_0 -> \pi^+\pi^-) = (0.86 \pm 0.27
(\rm stat) \pm 0.15 (\rm syst))\times 10^{-6}$, corresponding to $149 \pm 49$
$B^0 -> rho^0 f_0$ events with a significance of 3.0 standard deviations and
upper limits at 90% confidence level on the (product) branching fractions for
possible decays with the same final state, ${\cal B}(B^0 -> pi^+\pi^-pi^+\pi^-)
< 11.7 \times 10^{-6} $, ${\cal B}(B^0 -> rho^0 pi^+\pi^-) < 12.2 \times
10^{-6}$, ${\cal B}(B^0 -> f_0 pi^+\pi^-) \times {\cal B}(f_0->\pi^+\pi^-) <
3.1 \times 10^{-6}$ and ${\cal B}(B^0 -> f_0 f_0) \times {\cal
B}(f_0->\pi^+\pi^-)^{2} < 0.2 \times 10^{-6}$.
12/2012;
-
R Mizuk,
D M Asner,
A Bondar,
T K Pedlar,
I Adachi,
H Aihara,
K Arinstein,
V Aulchenko,
T Aushev,
T Aziz, [......],
M Watanabe,
Y Watanabe,
K M Williams,
E Won,
B D Yabsley,
J Yamaoka,
Y Yamashita,
C Z Yuan,
Z P Zhang,
V Zhilich
[show abstract]
[hide abstract]
ABSTRACT: We report the first evidence for the η_{b}(2S) using the h_{b}(2P)→η_{b}(2S)γ transition and the first observation of the h_{b}(1P)→η_{b}(1S)γ and h_{b}(2P)→η_{b}(1S)γ transitions. The mass and width of the η_{b}(1S) and η_{b}(2S) are measured to be m_{η_{b}(1S)}=(9402.4±1.5±1.8) MeV/c^{2}, m_{η_{b}(2S)}=(9999.0±3.5_{-1.9}^{+2.8}) MeV/c^{2}, and Γ_{η_{b}(1S)}=(10.8_{-3.7-2.0}^{+4.0+4.5}) MeV. We also update the h_{b}(1P) and h_{b}(2P) mass measurements. We use a 133.4 fb^{-1} data sample collected at energies near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider.
Physical Review Letters 12/2012; 109(23):232002. · 7.37 Impact Factor
